Formation perforator



p 3, 1969 E. JOHNSON FORMATION PERFORATOR 2 Sheets-Sheet 1 Filed Sept.5, 1967 WA//////////// //u INVENTOR. HARO'LD E, JOHNSON ATTORNEYS p 3,1969 E. JOHNSON FORMATION PERFORATOR 2 sheets-Sleet 2 Filed Sept. 5,1967 (a fa- INVENTOR. HAROLD E JOHNSON ATTORNEYS United States Patent O3,468,386 FORMATION PERFORATOR Harold E. Johnson, 4318 Harvard, Midland,Tex. 79701 Filed Sept. 5, 1967, Ser. No. 665,640 Int. Cl. E21b 43/117,33/12 U.S. Cl. 175-4.6 9 Claims ABSTRACT OF THE DISCLOSURE A formationperforating apparatus is secured sealingly in an opening of a casng subin a manner that the face of the perforator is unobstructed by thecasing shell so that a shaped charge or perforating bullet containedwithin the perforator does not have to penetrate the casmg upondetonation. The perforator is detonated by Primacord or detonating wirefrom the surface. The perforator This invention relates to theproduction of hydrocarbons and more particularly to the perforation ofsubterranean formations capable of producing oil or gas. Still moreparticularly, this invention relates to an apparatus for perforating aproducng formation, such as an oil producing formaton, to stimulate theproduction of fluid therefrom.

After a productive formaton, one capable of producing oil or gas, hasbeen drilled to the chosen depth, a casing is inserted down the lengthof the borehole and the space between the exterior surface of the casingand the interier surface of the borehole is filled with cement. Then, inorder to produce fluid from the well, explosive charges or bulletperforators are lowered down the well to a position opposite theproductive formation and the explosives are set ofl. The explosivecharges or bullets make puneture holes through the casing and cementliner and penetrate into the formation permitting the well fluid to flowinto the casing and be produced. 'Ihs process is referred to ascompleting the well. The greatest disadvantage of this process is thatthe explosive charge or bullet must penetrate the casing and the totalthickness of the cement liner before the productive formation isreached.

The primary object of this invention is to provide a more effectivemeans for perforating a productive formation. Another object of thisinvention is to provide a means for the perforaton of a productiveformation in a manner that the perforating means does not have to firstpenetrate the casing.

Still another object of this invention is to provide a means forselectively closing open portions of the well casing after theperforation operation has been carried out.

Further objects and advantages of the nvention will become apparent fromthe following description and claims, and from the accompanyingdrawings, wheren:

FIGURE 1 is a sectional view of a borehole illustratng one manner inwhich an apparatus of this invention may be used.

FIGURE 2 is an enlarged sectional view of a shaped charge apparatus usedaccording to this invention.

FIGURE 3 is a sectional View of another embodiment of a shaped chargeapparatus according to this invention.

3,468,386 Patented Sept. 23, 1969 FIGURE 4 is a longitudinal sectionalview of still another embodiment of a shaped charge according to thisinvention.

FIGURE 5 is a sectional view of still another embodiment of a shapedcharge according to this invention.

FIGURE 6 is a view along the lines 6--6 of FIG- URE 5.

FIGURE 7 is an elevational view of a shifting tool for positioning asleeve valve of this invention.

This invention comprises the placing of explosive devices, such asshaped charges or perforating guns sealingly in openings in the casingof a well in a manner that when the casing is put in place and the wellis cemented, only a thin portion of cement is present between theexplosive device and the face of the productive formation. Thus, theshaped charge or bullet need penetrate only a small thickness of cementin order to reach the productive formation. The explosive nnits arepreferably ignited by Primacord or detonating wire in a remote mannerfrom the surface. When shaped charges are used, the housing for thecharge disintegrates after exploding, and if desired, a sliding sleevevalve may be selectively positioned over 'any of the openings resultingfrom the shot.

Referring now to the drawings in detail, a borehole 10 is shown drilledthrough a productive formation 12. Conventionally, after the well isdrilled, casing is set in place and the interval between the casing andthe face of the borehole is filled with cement. In the figures, asection of casing 14 is shown in position down the' borehole 10 and issurrounded by cement 16 which is used to seal oli formation fluids fromthe well. Through openings 18 in casng 14 are positioned perforators 20which are shown in the drawings to be of the type employing a shapedcharge, but could also be of the type incorporating perforating bullets.It is preferred to use the shaped charge perforator since the perforatorhousing is designed to disintegrate upon explosion. 'Ihe perforator 20slips into an O-ring seal adapter 22 which is external of the casing,and preferably the perforator 20 and O-ring seal adapter 22 abut againsta retaining shoulder 24 for increased stability. O-rng seal adapter 22may be held in place removably as by threads, but preferably, it isgenerally more convenient to weld the O-ring seal adapter 22 intoposition on the casing. Perforator 20 is designed to fit closely intoO-ring seal adapter 22, and for holding the perforator in a sealableposition a recess 26 is formed in O-ring seal adapter 22 and acompressible O-ring 28 of a material such as Neoprene fits into recess26 and is compressed slightly by surface 30 of perforator 20. O-ringseal adapter 22 includes a recess 32 into which a clip ring 34 isinserted after perforator 20 is in position by means of which clip ring34 holds perforator 20 in place. Protruding through casing 14 is aconical portion 36 of perforator 20 which is of substantially thickerwall section than a front wall 38 of perforator 20. Front wall 38 isformed purposely thin so that it will be easily frangible. Comicalsection 36 is given its conformation in order to provide the propergeometry for a shaped charge 40 formed within perforator 20. shapedcharge 40 is held in position by a thin Copper liner 41. 'Ihe explosivematerial forming the shaped charge may be any of the conventionalexplosives generally used in such shaped charges. At the apex of theconically shaped charge is positioned a booster charge 42 of explosivewhich is employed to detonate the main body of explosive. An axialpassageway 44 provides communication between booster charge 42 and atransverse passageway 46 through which passageway 46 passes a detonatingmeans such as Primacord 48 which is ignitable from the interior of thecasing 14 and remotely ignitable from the surface of the ground. Thatis, an ignition means may be positioned within the casing &468386 closeto the perforator and may be controlled from the surface of the groundfor safety. Primacord is shown as a preferred ignition means, but otherignition means such as detonating `wire may be used to set off thebooster charge and shaped charge.

In using the perforator of this invention the location of the productiveformation should be accurately determined in order that the casing subcontaining the' desired number of perforating units may be properlylocated. Well logging and other related conventional measurements may beemployed in selecting the most desirable location of the perforatingunits as well as the number and type of units to be employed. One mannerof positioning the formation perforator casing sub is to attach a casingfloat collar or casing cementing adapter to the bottom of a section ofcasing of slightly less total length than the distance from the bottomof the hole up to the position chosen to be the lower end of the casingsub. Primacord or detonating wire is attached to each of the perforatingunits employed and the perforating casing sub is lowered into the holepreferably before the detonating unit 50 is attached. The detonatingunit 50 may be of any conventional type usable' with the explosivechosen for the perforators, that is, a mechanical, electrical, or timingdevice type detonator, and may also be retrievable. After properpositioning of the formation perforating casing sub a locating devicesuch as a gamma ray logging tool having a collar locator may be run downthe borehole to check the positioning of the perforating units beforecompleting the operation. If the position of the perforating units iscorrect, the casing may be cemented in place and after the cement cures,the explosive perforator may be detonated.

It is preferred that the perforator 20 be made of a material which willdisintegrate upon explosion of the shaped charge so that the opening 18in the casing wall will be clean and free of debris. Such a materialwould be diecast aluminum or an easily frangible ceramic. Afterdetonation, a closure device, such as a sliding O-ring sleeve valve 52comprisng a tubular section 54 having a close fit against the interiorwall of the casing 14, may be moved into position over opening 18 inwhich a perforator 20 has just been exploded. O-ring sleeve valve 52includes a circumferential recess 56 near each end of the cylindricalvalve into which is placed an O-ring 58 to provide sealing engagementwith the interior wall of casing 14. O-rirg sleeve valve 52 is slid intoposition over opening 18 and in its closed position abuts a stop 60adjacent opening 18. In the drawing stop 60 is shown in FIGURES 1 and 2of rectangular crdss-sectional configuration for the sake of clarity. Inmost installations stop 60 is more suitably formed with an angular orrounded cross-sectional conformation which will facilitate the operationof a sleeve shifting tool and also cause the stops to be less subject todamage from well bore equipment. Sliding O-ring sleeve valve 52 may beoperated from the surface by means of a sleeve shifting tool similar tothat shown in FIGURE 7. Such a shifting tool is run on a -wireline, rodstring, or tubing string. Sleeve valve 52 may be operated selectively sothat a chosen number of openings 18 may be covered or uncovered asdesired. FIGURE 1 shows, for the purpose of illustration, how a sleevevalve 52 may be brought into a closed position over opening 18 in orderto prevent communication between a perforation 64 and the interior ofcasing 14. Of course, sleeve valve 52 is shown in a simplified form forthe sake of illustration and suitable variations in the valve structureare within the scope of this invention. FIGURES 3, 4, 5 and 6 showadditional embodiments of shaped charge apparatus prepared according tothis invention. In the embodiment shown in FIGURE 3 the shaped chargedevice is positioned substantially eXteriorly of the casing to which itis attached. A bore 66 is formed in the wall of casing 14 and a threadedmounting boss 68 is inserted through the bore 66 from the exterior ofthe casing and is held in place by cooperation of a retaining nut 70threadably engaging the mounting boss. On the eXterior of casing 14 theperforated device includes a thick-walled housing portion 72 preferablymade integral with mounting boss 68. Housing 72 has a concave rearsurface 74 which permits abutment of the housing with the exterior wallof the casing. inside the housing 72 is positioned a shaped charge 76which is held in place by a thin frangible wall. 78. Mounting boss 68has a hollowed-out portion which is occupied by a booster charge 80 soarranged to detonate shaped charge 76. A passageway 82 is provided tocommunicate with a bore portion 84. Booster charge 80 communcatesthrough passageway 82 with a length of Primacord which is positionedthrough bore 84. Thus, in operation the shaped charge described inFIGURE 3 is ignited in the same manner as described in the embodiment ofFIGURE 2.

In FIGURE 4 is shown an elongated perforating apparatus in which theshaped charge is positioned longitudinally along the casing.

An elongated perforator 86 is positioned exteriorly on the casing 14 andis supported at an upper and lower extremity by a conventional clampingband 88 which can be positioned around the casing and perforator byconventional means, such as a machine nut and bolt, and arranged to holdthe perforator in position by cooperation with an extension 90 of theperforator housing. In cross-section elongated perforator 86 is similarto the cross-section of the perforator shown of FIGURE 3.

FIGURES 5 and 6 show still another variaton of exteriorly positionedperforators according to this invention. In this embodiment theformation perforator is positioned around the external periphery of thecasing 14. Although a series of arcuate perforators could be positionedaround the exterior periphery of the casing, the most convenient andpreferred Construction is to use perforators which are essentiallysemi-circular in shape as shown in FIGURE 5. The semi-circularperforators 92 are held in position abutting the casing 14 in the samemanner as the perforators shown in FIGURE 3. That is, a mounting boss 94is inserted through a bore 96 in casing 14 and is held in position bythe cooperation of a retaining nut 98 with threads 100 on mounting boss94. FIGURE 6 is a longitudinal section view of the semi-circularperforators of FIGURE S and in cross-sectional view shows theseperforators to be constructed essentially like the perforators of FIGURE3.

FIGURE 7 shows a shifting tool 102 usable with the Sliding valve 52 ofthis invention in positioning valve 52 after formation perforation hasbeen aceomplished. Shifting tool 102 includes a body portion 104 towhich is attached a shifting dog 106 and a one-way release trigger 108.shifting dog 106 has protruding therefrom a cocking cam 110, a releasingcam 112, and a shoulder 114. Oneway release trigger 108 is spring-loadedand ratchet controlled so that the trigger is biased to rotatecounterclockwise. The shifting tool is run into the casing with shiftingdog 106 in a retracted cocked position. When the one-way releasedtrigger 108 contacts upper valve stop 116 the release trigger is rotatedcounterclockwise to release the lease dog. The tool is then lowereduntil shoulder 114 approaches lower valve stop 116. Then the directionof movement is reversed so that shoulder 114 is brought into abutmentwith the lower portion of sleeve valve 52 and the shifting tool raisesthe sleeve valve to its closed position. At this time the shifting dogis automatically released when releasing cam 112 is forced over uppervalve stop 116. Shoulder 114 then slides through sleeve valve 52 and thetool can be extracted. If, instead of raising the shifting tool when thesleeve valve is closed, the shifting tool is again moved downward,cocking cam will contact upper valve stop 116 and the shifting dog canbe returned to the retracted position by the rotation of release trigger108 to its initial cocked position.

&468386 Since many different embodiments of this invention may be madewithout departing from the spirit and scope thereof, it is to beunderstood that the specific embodiments described in detail herein arenot to be taken in a limiting sense, since the scope of the invention isbest de fined by the appended claims.

What is claimed:

1. A formation perforator comprising:

a casing section positionable in a borehole adjacent a productiveformation, said casing having an opening in the wall thereof oppositesaid productive formation,

perforator means sealingly positonable in said opening of said casingadjacent said productive formation,

means operable from within said casing for actuating said perforatormeans, and

a sliding sleeve valve interiorly of said casing and positionableadjacent said opening in said casing Wall, said valve operable fromwithin said casing by means controllable from the surface of the groundto position said valve to sealngly cover said opening.

2. A formaton perforator as described in claim 1 in which:

said perforator means includes a housing containing a shaped explosivecha'ge.

3. A formation perforator as described in claim 1 wherein said housingcontaining said shaped explosive charge is positioned substantallyexteriorly of said casing.

4. A formation perforator as described in claim 3 wherein said housingcontaining said shaped explosve charge comprises an elongated housingpositioned parallel to the longitudinal axis of said casing.

5. A formation perforzlor as described in claim 3 wherein said housingcontaining said shaped explosive churge comprises an elongted housingpositioned 'adially around said casing substantially normal to thelongtudnal axis of said casing.

6. A formation perforator as described in claim 1 wherein said housingcontaining said shaped explosive charge is positioned in said openingsubstantially interiorly of said casng.

7. A formation perforator as described in claim 6 wherein said housingcontaining said shaped charge includes a thin-walled front portionfacing exteriorly of said casing and a thick-walled conical fear portionfacing interiorly of said casing, a booster explosive charge positionedadjacent said shaped explosive charge, a transverse passageway adjacentthe apex of said conical portion, and ignition means passing throughsaid transverse passage- Way to set off said booster charge, saidignition means ignitable from within said casing.

8. A formation perforator as described in claim 7 in which said housingis removably positiona-ble in said casing, said casing includes aretaining shoulder refining said opening and against which said housingabuts, an O-ring seal adapter adjacent said opening exteriorly of saidcasing for holding said housing in sealable alignment, and a clip-ringretainer to hold said housing in tight engagement against said retainingshoulder.

9. A formation perforator as described in claim 8 in which said ignitionmeans includes a wire-line ignitor assembly.

References Cited UNITED STATES PATENTS 2,201,290 5/1940 Greene 166-35 X2,500,754 3/1950 Huber 175-4.52 X

2,587,244 2/1952 Sweetman 175-4.6

2,725,942 12/1955 McCullough 166-37 X 2,775,304 12/1956 Zandmer 166--1002,873,676 2/1959 Caldwell 175-4.6

2,939,532 6/1960 Morriss 166-63 3,270,8l4 9/1966 Richardson et ai.166-100 X 3,336,759 8/[967 Copper 166-35 X 3,357,504 12/1967 Calhoun175-4.52

DAVID H. BROWN, Primary Examiner U.S. Cl. X.R. 166-63,

